? Could someone please look something up in the braunbuch ?

I have here a very rare U73 type.

I know and own the regular U73 and U73b types but the one I have is a very early version with microphone input.

I only have access to the braunbuch index and found some lines that could be of interest.

especially the first and third line. Dated  02/05/1957 and 03/07/1957.

could someone make me a copy of the actual schematics and info.

 

I've attached the index of the actual pages in the braunbuch. That's all I have.

Danke

Attachments:

• Untitled (642 KB)

To thank the Author because you find the post helpful or well done.

Dear Kris,

the documents you are asking for are not part of the Braunbuch. One is a document from the manufacturer TAB, the other one an internal document of the IRT. What has found its way into the Braunbuch is the document in the second line. That document (24pp. in my edition) does not contain any information regarding a previous version of the U73.

Having a microphone input on a U73 does not sound like something that would make sense within the concept of the V70 family, unless it was some derivative for talkback mic, like the later U474A.

Maybe it would be helpful if you posted pictures of your unit, showing type label an connections.

 

Nikolaus Löwe

 

To thank the Author because you find the post helpful or well done.

hello Nikolas.

thank you for the reply.

as you can see there is an extra tube for the mic preamp gain and a Malotki 1:30 tranformer.

My guess is that they were made in house by the IRT.

 

any more guesses or info welcome

 

I

To thank the Author because you find the post helpful or well done.

Tubes are 2x ECC82, 2x 6BA6 and a E88CC for sidechain/ gain reduction.

 

To thank the Author because you find the post helpful or well done.

I know many if not all the U and V series but it's the first time I come across a version like this.

Everything works fine and connection is the same as the more common models.

I don't think they are somehow modified because the mounting and PCB is properly done.

To thank the Author because you find the post helpful or well done.